RowdyTI

When I spin my rear wheel I notice the rotor has a slight wobble from side to side. I had this on my old bike as well. What causes this and how typical is it? The rotor isn't warped.

ljsense

If all the bolts or the centerlock ring holding the rotor to the hub are tight, and they'd better be, it is warped or bent. If it weren't, it would spin true and round.

It's pretty common. Probably the most common cause is something hitting the rotor. Sometimes it happens when the wheel is off the bike, or being reinstalled. Sometimes the bike just hits something, like a stump in a crash.

RowdyTI

Shimano Deore SM-RT56 6-Bolt Disc Brake Rotor silver: 180 mm

Can I use this for my Tektro disc brakes with 180 mm Tektro rotors? I believe this is a bit higher quality. Any issues using it as a replacement for my Tektro brakes?

dsbrantjr

Having a wobble form side to side is kind of the definition of warped. A warped rotor can be trued, I use a long-nosed Vise-Grips but an adjustable wrench or rotor truing tool can also be used.

grizzly59

It may be the machining of the bolt circle on the hub isn't perfect in relation to the axle. Axle may not be normal to the plane of the disc, or the hub mounts aren't all in the same plane. The outer nuts on the hub can be a little goofy as well. If you loosen the skewer and rotate the axle 90deg, then tighten the skewer back up, what does the disk look like when you spin the wheel?

Cyclist0108

It will work. I have done it. Some Tektro/TRP brakes will allow you to use Shimano pads, which will likely also be an improvement.

RowdyTI

Well, on one rotation of every rear wheel spin, I hear a noise, but the rotor is never touching the brake pads. That's not what the noise is coming from. I just tend to think with a big mountain bike tire, that some subtle wobble of the disc rotor is more normal than not even on perfectly new compnonents. If you have a mountain bike with a rotor that rotates perfectly straight when carefully inspected, I'd consider that a marvel and would like seeing a video.

RowdyTI

Yes, I just had another look. The whole cassette on that rear wheel has some wobble to it. It has to do with how the wheel is spinning, which has that slight wobble. Again, I'm guessing this is more normal than not. Those of you with mountain bikes, does your rear wheel really rotate perfectly?

One says, "I have four bikes, 3 speshs, 1 salsa, all of them have a slight side to side wobble on the cassette when the rear wheel is freehubing. To notice it I have too look really closely when I have them on the work stand. I have not felt any issues due to this wobble while riding them. They all shift super smooth and quickly and never ghost shift."

Another: "I've not seen a cassette that doesn't do this, IMO they all do it to some degree as the cassettes floats on its bearings unless the pawls are engaged. Some say it's by design perhaps to aid with gear changes etc. I used to have £2000 road bike with custom built wheels that used to do the same thing, it never caused any trouble even after many thousands of miles riding. Unless it's causing specific issues I wouldn't worry about it."

One more: "My brand new bike with a cassette did this and when I got a brand new wheel/cassette, it also wobbled."

I believe this is directly related to the slight rotor movement I see even though the rotor looks perfectly straight.

shelbyfv

To clarify, both your rotor and cassette are wobbling and something (but not the disc) is making a noise each rotation. Is that accurate?

trailangel

IMO you should have absolutely zero play concerning the rotors Same with the cassette...zero play. Maybe your bearings are too loose.
Play or wobble.... which is it?

RowdyTI

Yes, that sounds right.

See this of another report:

https://forums.thepaceline.net/showthread.php?p=2080214




I tend to think it has to do with the wheel having a hop due to imperfect mounting that is quite normal with big mountain bike tires, but I could be wrong. When the big mountain bike tire rolls around and isn't absolutely perfectly mounted, it may cause this slight hobble because it has quite a big rotational mass. I haven't thought that through very much though and like I say could be wrong.

Any thoughts?

One says, "Is it normal? Well, it's not unusual. Shimano's freehubs are notorious for having wobble. And wobble is amplified by the sprocket size, so the bigger the sprocket, the bigger the lateral excursions."

Another says: "I have Ultegra wheels and the rear wheel cassette easily wobbles that much. Maybe more. The bike shop said no problem and they were right: I put about 2000k on those wheels and the shifting was always problem free and crisp.

I can't say the same pleasant things about the wheels overall, which frequently came out of true and, just at the end of the summer, a spoke broke. I weigh a lot (215ish) so that may have been a factor, but I was pretty careful about what kinds of roads I went on with these wheels, so it surprised me. The hub also sounded scratchy right from day 1, so I wasn't really happy with these wheels. They are easy to service, so points for that, but they cost too much to need that kind of TLC so early in their life.

None of my other wheels (Mavic, Giant and DT Swiss) have any wobble (or broken spokes/problems with trueness). Just saying."

RowdyTI

Also found this: The Freewheel Wobble - Why A Cassette Won't - BikemanforU Tutorial

Yes, the title isn't correct, it's wobble, not play. My previous bike had more wobble of the rotor than this one. I believe it's more common than not on mountain bikes, and not related to warped rotors.

shelbyfv

You could test this by removing the tire, spin the wheel etc w/o the tire. If it still wobbles it's in the wheel not the tire.